1+3/2与1+1/2对转涡轮对比分析

为理清1 1/2对转涡轮及1 3/2对转涡轮使用范围和效能,从而帮助设计决策,本文采用Stewart方法,从速度三角形基本分析入手,以速功比为主要变量,考察、对比1 3/2和1 1/2对转涡轮性能特点.研究表明:各转速比下,1 3/2对转涡轮高效率范围都比1 1/2对转涡轮窄,但其高效区发生在更小的总速功比区域;随转速比绝对值增加,两种涡轮高效率区都增加,高效率区位置都偏向大的总速功比区域;相比于1 1/2对转涡轮,1 3/2对转涡轮具有较低出功比,且偏向于低速功比区域;随转速比绝对值增加,两种对转涡轮出功比范围均拓展.这些结果为未来先进航空发动机涡轮选型提供了重要借鉴.

BASIC ANALYSIS ON 1+3/2 AND 1+1/2 COUNTER-ROTATING TURBINES

In order to understand the performance and the range of application of two types of Vaneless Counter-Rotating Turbines(namely 1 1/2 and 1 3/2 stages VCRT) and then help making decision in engine design,the two types of VCRT are analyzed in terms of work speed ratio.The performance comparison of these two types of VCRT reveals many useful results.In all ranges of shaft speed ratio,the high efficiency region in work speed ratio of 1 3/2 stages VCRT is narrower than 1 1/2 stages VCRT,but the high efficiency region of 1 3/2 stages VCRT is always located in range of lower work speed ratio.As compared with 1 1/2 stages VCRT,1 3/2 stages VCRT has a lower shaft work ratio,and can provide much more work.Shaft speed ratio(high pressure shaft over low pressure shaft) itself also exerts great influences on the efficiency and the application range of these two types of VCRT.As the absolute value of shaft speed ratio increases,high efficiency region always moves to the region with a higher total work speed ratio,and the shaft work ratio will also increase.All these results are used for reference in selecting turbine configurations in design of advanced aero engines.